With the increasing development of science and technology, computers have become an indispensable part of people's lives. In order to expand the capabilities and links of computer, all kinds of expansion cards, such as memory devices or interface cards, are usually inserted and set on the main circuit board of the computer. After the expansion cards are inserted in the configuration of the main circuit board of the computer, the computer is rebooted for performing a testing. When there is a fault or incompatibility problem, the computer must be shut down to re-install or replace the expansion cards, and repeatedly execute the aforementioned processes for testing. However, with the repeated processes to start up and shut down the computer for testing and installing the expansion cards, the entire system won't be expanded conveniently, and the repeated processes might further lead the electronic devices thereof to be broken. Thus, an expansion card combined with a light-emitting device is provided in the market. The light-emitting device is used for indicating the compatibility of the expansion card inserted and set on the main circuit board of the computer, identifying the using status of the expansion card or determining if the expansion card is out of order according to the status of emitting the light. Certainly, the light-emitting device can be used as a decorative lighting for providing a kind of visual enjoyment merely. But such light-emitting device usually emits uneven light beams and causes the partial brightness problem.
On the other hand, for solving the heat dissipation problem, heat-dissipating devices can be configured and disposed on the expansion card directly. However, the light beams emitted from the aforementioned light-emitting device are usually influenced by the disposition of such heat-dissipating devices. Consequently, the uneven brightness is caused and the entire illumination efficiency is influenced.